Reverse charging system, reverse-charging service control apparatus, call agent and reverse charging method

ABSTRACT

A call agent (CA) connects a IP telephone and a public switching telephone on the basis of a called-destination telephone number which corresponds to received reverse-charging service number from the IP telephone; a reverse-charging service control apparatus causes an exchange to stop charging; the CA and the reverse-charging service control apparatus calculate a charging information items, respectively; and generate a fee information by setting a charged party information so that a sum of fees in an IP network and a public switching telephone network may be charged to the called-destination telephone number, and transmit the fee information to an IP/PSTN charging management apparatus on a called destination side; and generate other fee information so that a fee in the network on a call origination side may be charged to a business company of called destination, and transmit the fee information to the apparatus on a call origination side.

CROSS REFERENCE TO RELATED APPLICATION

This is a continuation of U.S. application Ser. No. 10/914,312, filedAug. 10, 2004, the entirety of all of the contents and subject matter ofwhich are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a reverse charging system, areverse-charging service control apparatus, a call agent and a reversecharging method. More particularly, it relates to a reverse chargingsystem, a reverse-charging service control apparatus, a call agent and areverse charging method for providing a reverse charging service in atelephone network which is capable of interconnecting IP telephone setsand public switching telephone sets.

2. Description of the Related Art

In the existing PSTN (Public Switching Telephone Network), exchangesoperate in concert with IN (Intelligent Network) apparatuses through acommon channel signaling system, whereby telephone services of highfunctions are provided.

One of the telephone services is a reverse charging service which iscurrently rendered in the PSTN, and which uses special numbers beginningwith a number “0120”. The reverse charging service in the PSTN is statedin, for example, JP-A-2001-309088. In an invention stated in thisdocument, telephone numbers for reverse charging and the calleddestination telephone numbers of service contractors are registered in adatabase for providing the reverse charging service. In a case where acall to any service contractor has originated, an exchange whichaccommodates a call originating terminal identifies the calleddestination telephone number to be a subject for the reverse chargingservice, and it notifies the reverse-charging telephone number to anetwork service control station which is a kind of IN apparatus. Thenetwork service control station searches the database for the calleddestination telephone number corresponding to the reverse-chargingtelephone number, it notifies the sought destination telephone number tothe originating exchange, and it performs a calling connection processfor the destination telephone number. At the same time, the networkservice control station instructs the originating exchange not to chargea call fee to the call originator. When telephonic communication hasended, the network service control station generates fee information inwhich the called destination telephone number is set as the chargedparty of a call fee, and it transmits the information to a billingcenter.

The reverse charging service is provided in the PSTN by the method asstated above. In recent telephone networks, the PSTN and IP (InternetProtocol) networks are being merged. It is desired to render the varioustelephone services having been provided in the PSTN, also for IPtelephone sets.

Besides, in general, in the connection between the PSTN and the IPnetwork, the interconnection is realized by installing a media gateway(MG) which cross-converts the STM (Synchronous Transfer Mode) voicesignal data of the PSTN and IP voice packets, a signaling gateway (SG)which connects a common channel signaling network and the IP network soas to transmit and receive control signals, and a call agent (CA) whichconverts a common channel signal received by the SG, into a signal foran MG control conforming to an MGCP (Media Gateway Control Protocol), soas to perform the MG control. These techniques are stated in, forexample, “Nikkei Communications”, Issue of Aug. 7, 2000, p. 104-p. 105.

This connection system will be outlined. First, in a case where an IPtelephone subscriber has originated a call from an IP telephone to aPSTN subscriber telephone, the CA receives the calling source telephonenumber of the IP telephone being a call originator, and a calleddestination telephone number. Subsequently, the CA searches a databasefor the IP address of the MG connected with an exchange whichaccommodates the PSTN subscriber telephone being a called destination,on the basis of the toll number of the received called-destinationtelephone number, and it is connected with the MG. Further, the CA isconnected with the exchange on the basis of the called destinationtelephone number so as to permit telephonic communication with the PSTNsubscriber telephone.

Besides, regarding charging based on the connection between the PSTN andthe IP network, another document states a charging system wherein a CAcalculates a rental fee involved in an IP network and a connection feearising between the IP network and an exchange, and an IP businesscompany demands the payment of the fees from an IP telephone owner,while the exchange which accommodates a PSTN subscriber telephone beinga called destination calculates the rental fee of the exchange, and thePSTN demands the payment of the rental fee from the IP business company.This technique is stated in, for example, “Nikkei Communications”, Issueof Mar. 3, 2000, p. 89.

SUMMARY OF THE INVENTION

In a case where, in conformity with the prior-art connection system andcharging system as explained above, a reverse charging service is to berendered in call reception at a PSTN subscriber telephone as based oncall origination from an IP telephone, there are problems as statedbelow.

Usually, a CA acquires the information of a called destination telephonenumber in response to the call origination from the IP telephone, and itacquires the IP address of an MG connected with an exchange whichaccommodates the PSTN subscriber telephone being a called destination,on the basis of a toll number. As the problem #1, however, a routingnumber (for example, number “0120”) which indicates reverse charging isnot an office number, so that the CA in the prior art cannot specify theexchange (or MG) being a connection destination.

Further, the charging method in the related art has the problem #2 that,since the PSTN subscriber telephone set being a reverse-charging servicecontractor is not a telephone set existing in an IP network, the CA ofan IP business company cannot specify a business company and thecontractor being a demandee for the payment of a fee. By way of example,in the case where a telephone call is made from the IP telephone to thePSTN subscriber telephone by the reverse charging, a fee involved in theIP network is charged to the PSTN subscriber telephone. Since, however,the IP business company does not know the name, address, etc. of thePSTN subscriber, it cannot directly demand the payment of the fee.

Besides, the related-art charging system has the problem #3 that theexchange cannot alter the charged party for the connection fee betweenthe business sites of this exchange and the MG, from the calloriginating business company to the call destination business company.In the case of, for example, the connection from the side of the IPnetwork to the exchange, the prior-art charging system is contrived tocharge the connection fee between the business sites, to the IP businesscompany being the originating business company. The reverse chargingcannot be realized using the exchange as it is.

On the other hand, in a case where a reverse charging service is to berendered in call reception at an IP telephone as based on callorigination from a PSTN subscriber telephone, there is the problem #4that, since the IP telephone being a reverse-charging servicecontractor. is not a telephone set existing in the PSTN, the PSTNbusiness company cannot specify a demandee for the payment of a fee.

Moreover, problems similar to the problems #1-#4 which are posed inrealizing the reverse charging between the IP telephone and the PSTNsubscriber telephone can occur also in case of realizing reversecharging between different IP telephone business companies.

In view of the above drawbacks, the invention has for its object toprovide a reverse-charging service control apparatus and system forrealizing a reverse charging service in a telephone network in which IPtelephone sets and public switching telephone sets can beinterconnected.

The above problem #1 is solved by installing a CA which has thediscrimination function of recognizing the routing number for thereverse charging service as is contained in the called destinationtelephone number having received the call origination from the IPtelephone, thereby to discriminate whether or not the pertinent call isof the reverse charging service, and a reverse-charging service controlapparatus which has the functions of receiving from the CA the numberfor the reverse charging service, searching a table where numbers forthe reverse charging service and called destination telephone numbersare held in correspondence, and sending the called destination telephonenumber to the CA in reply.

Regarding the problem #2, the demandee for the payment can be specifiedin such a way that the reverse-charging service control apparatusinstructs the CA for charging the rental fees of the IP network and theexchange, to alter a charged party to the called destination telephonenumber of the reverse-charging service contractor, that the CA generatesfee information, in which the called destination telephone number of thereverse-charging service contractor is set as the charged party, andthen transmits the fee information to the PSTN charging managementapparatus through the reverse-charging service control apparatus, andthat the telephone number of the reverse-charging service contractor setas the charged party is searched for by the PSTN charging managementapparatus.

The problem #3 can be solved in such a way that, in the reverse chargingservice, the reverse-charging service control apparatus performs thecontrol of bringing the charging status of the exchange into thenon-charging status thereof, and that the reverse-charging servicecontrol apparatus charges the rental fee of the exchange and sets as thecharged party the called destination telephone number of thereverse-charging service contractor as stored in the apparatus itself.

Regarding the problem #4, the demandee for the payment can be specifiedin such a way that, in the reverse charging service, thereverse-charging service control apparatus performs the control ofbringing the charging status of the exchange into the non-chargingstatus thereof, that the reverse-charging service control apparatuscharges the rental fee of the exchange and generates fee information inwhich the called destination telephone number of the reverse-chargingservice contractor is set as the charged party, so as to transmit thegenerated fee information to the IP charging management apparatus, andthat the telephone number of the reverse-charging service contractor setas the charged party is searched for by the IP charging managementapparatus.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF DRAWING

FIG. 1 is a diagram showing an architectural example of theinterconnection network between an IP network and a PSTN as is furnishedwith a reverse-charging service control apparatus;

FIG. 2 is a diagram showing a block configurational example of a callagent;

FIG. 3 is a diagram showing a block configurational example of thereverse-charging service control apparatus;

FIG. 4 is a diagram showing an example of a fee charging database whichis included in a PSTN charging management apparatus;

FIG. 5 is a diagram showing an example of a fee charging database whichis included in an IP charging management apparatus;

FIG. 6 is a diagram showing an example of a database for a reversecharging service as is included in a called-destination-number storageunit;

FIG. 7 is a diagram showing an example of a database which is includedin a routing-number discrimination unit;

FIG. 8 is a diagram showing an example of a database which is includedin an IP-address storage unit;

FIG. 9 is a diagram showing an example of a database which is includedin a terminal discrimination unit;

FIG. 10 is a diagram showing an example of a database in a fee-ratediscrimination unit;

FIG. 11 is a diagram showing a sequence (call origination from an IPtelephone) in the reverse charging service;

FIG. 12 is a diagram showing a flow chart (1) (call origination from theIP telephone) illustrative of the operation of a CA in the reversecharging service;

FIG. 13 is a diagram showing a flow chart (2) (call origination from theIP telephone) illustrative of the operation of the CA in the reversecharging service;

FIG. 14 is a flow chart (call origination from the IP telephone) showingthe operation of the reverse-charging service control apparatus in thereverse charging service;

FIG. 15 is a diagram showing a sequence (call origination from a PSTNsubscriber telephone) in the reverse charging service;

FIG. 16 is a diagram showing a flow chart (call origination from thePSTN subscriber telephone) illustrative of the operation of the CA inthe reverse charging service; and

FIG. 17 is a diagram showing a flow chart (call origination from thePSTN subscriber telephone) illustrative of the operation of thereverse-charging service control apparatus in the reverse chargingservice.

DETAILED DESCRIPTION OF THE INVENTION

First, a network architecture and an apparatus configuration will bedescribed. FIG. 1 is a diagram showing an example of the architecture(reverse charging system) of the interconnection network between an IPnetwork and a PSTN as is furnished with a reverse-charging servicecontrol apparatus. The reverse charging system includes a CA (callagent) 102, an MG (media gateway) 104, an exchange 106, thereverse-charging service control apparatus 107, a PSTN chargingmanagement apparatus 108, and an IP charging management apparatus 110.

An IP telephone 101, the CA 102 and the MG 104 are connected to the IPnetwork 103. The CA 102 is connected with a common channel signalingnetwork 105 so as to communicate control signals with the PSTN and toperform a call control. Also, it is connected with the IP chargingmanagement apparatus 110 which holds and manages, for example, charginginformation on individual IP telephones. On the other hand, on the sideof the PSTN, the exchange 106 which accommodates PSTN subscribertelephones 109 is connected with the MG 104, and it is connected withthe PSTN charging management apparatus 108 which holds and manages, forexample, exchange rental-fee information and charging information to thePSTN telephones.

The reverse-charging service control apparatus 107 is connected with theCA 102 and the exchange 106 through the common channel signaling network105 so as to control a calling connection process in a reverse chargingservice. Further, the reverse-charging service control apparatus 107 isconnected with the PSTN charging management apparatus 108 and the IPcharging management apparatus 110 so as to manage charging informationwith both the management apparatuses combined. Incidentally, it ispossible to install a plurality of CA 102, exchanges 106, etc. Besides,although FIG. 1 illustrates the case of one IP business company and onePSTN business company, it is also possible to lay out a system in whichpluralities of IP business companies and PSTN business companies areexistent. In this case, by way of example, the PSTN charging managementapparatus 108 or the IP charging apparatus 110 may well be installedevery business company.

FIG. 2 is a diagram showing an example of the block configuration of theCA 102 which has functions for realizing the reverse charging service.The CA 102 includes an IP-network interface 201, an SIP (SessionInitiation Protocol) process unit 203, a voice-guidance sending unit204, a voice-signal conversion unit 205, an IP-address storage unit 206,a common-channel-signal IP 207, a time monitoring unit 208, a fee-ratemanagement unit 209, a fee calculation unit 210, a routing-numberdiscrimination unit 211, an IP-charging-management-apparatus interface212, a charged-party management unit 213, and a CA control unit 202.Incidentally, the fee-rate management unit 209 and the charged-partymanagement unit 213 may well be appropriately provided within, forexample, the fee calculation unit 210 or the CA control unit 202.

The IP-network interface 201 is connected with the IP network 103 so asto transmit and receive the IP packets of call controlling data, voicedata, etc. The SIP process unit 203 executes, for example, an SIP(Session Initiation Protocol) as a call control protocol. Incidentally,an appropriate call control protocol such as “H. 323” may well beemployed otherwise than the SIP. The voice-guidance sending unit 204serves as a sound source for notifying the fact that a reverse-chargingservice number is not registered in the routing-number storage unit 211,to a call originator through voice guidance or the like. Incidentally,the data etc. of the voice guidance are registered in the voice-guidancesending unit 204 beforehand. The voice-signal conversion unit 205converts, for example, the data of the voice guidance into voice packetsin order to convey the voice guidance to the IP telephone 101 which isconnected via the IP network.

The correspondence table between the called destination telephonenumbers and IP addresses of individual subscribers is stored in theIP-address storage unit 206 beforehand. The common-channel-signalinterface 207 is an interface which is connected with the common channelsignaling network 105, and which serves to transmit and receiveinformation items such as a calling source telephone number and thecalled destination telephone number of a reverse-charging servicecontractor. The time monitoring unit (first time monitoring unit) 208monitors, for example, the talking time of the telephonic communicationbetween the IP telephone and the PSTN telephone. The fee-rate managementunit (first fee-rate management unit) 209 manages the fee rates of callfees as correspond to, for example, time periods, talking distances,etc. In this embodiment, the fee rates contain, for example, an IP feerate which indicates the fee of every predetermined time in the IPnetwork, and a PSTN fee rate which indicates the fee of everypredetermined time in the PSTN. Besides, the connection fee between thebusiness companies, namely, between the exchange and the MG as arises inthe case of connection from the IP network to the PSTN through theexchange can be contained in, for example, the PSTN fee rate. The feecalculation unit (first fee calculation unit) 210 calculates a call feeafter the end of telephonic communication, and it generates feeinformation which contains charged-party information and the fee(charging information). The routing-number discrimination unit 211stores the routing numbers of reverse-charging service numbers therein,and it discriminates whether or not a call is of reverse charging. TheIP-charging-management-apparatus interface 212 is an interface forconnection and communication with the IP charging management apparatus110. The charged-party management unit 213 manages the charged partiesof call fees in the reverse charging service. The CA control unit 202controls the various blocks within the CA 102.

FIG. 3 is a diagram showing an example of the block configuration of thereverse-charging service control apparatus which has functions forrealizing the reverse charging service. The reverse-charging servicecontrol apparatus 107 includes a common-channel-signal interface 301, aterminal discrimination unit 303, an IP-charging-management-apparatusinterface 304, a PSTN-charging-management-apparatus interface 305, acalled-destination-telephone-number storage unit 306, acalling-source-telephone-number storage unit 307, a time monitoring unit308, a fee-rate management unit 309, a fee calculation unit 310, areverse-charging-service-number storage unit 311, a fee-ratediscrimination unit 312, a charged-party-business-company storage unit313, a charging stop unit 314, and a reverse-charging control unit 302.Incidentally, the called-destination-telephone-number storage unit 306,calling-source-telephone-number storage unit 307, fee-rate managementunit 309, reverse-charging-service-number storage unit 311 andcharged-party-business-company storage unit 313, and the charging stopunit 314 may well be appropriately provided within, for example, the feecalculation unit 310 and the reverse-charging control unit 302,respectively.

The common-channel-signal interface 301 is an interface which isconnected to the common channel signaling network 105, and which servesto transmit and receive information items such as a calling sourcetelephone number and the called destination telephone number of areverse-charging service contractor. The terminal discrimination unit303 has a database in which terminal types (IP telephones or PSTNsubscriber telephones) are stored in correspondence with, for example,telephone numbers, and it discriminates the terminal types on the basisof the telephone numbers. The IP-charging-management-apparatus interface304 is an interface for connection with the IP charging managementapparatus 110. The PSTN-charging-management-apparatus interface 305 isan interface for connection with the PSTN charging management apparatus108. The called-destination-telephone-number storage unit 306temporarily stores therein the called destination telephone number of areverse-charging service contractor searched for from thereverse-charging-service-number storage unit 311. Thecalling-source-telephone-number storage unit 307 temporarily stores thetelephone number of a call originating terminal.

The time monitoring unit (second time monitoring unit) 308 monitors atalking time. The fee-rate management unit (second fee-rate managementunit) 309 manages the fee rates (for example, IP fee rate and PSTN feerate) of call fees as correspond to, for example, time periods, talkingdistances, etc. The fee calculation unit (second fee calculation unit)310 calculates a call fee after the end of telephonic communication.Incidentally, the time monitoring unit 308 and the fee-rate managementunit 309 can be endowed with the same functions as those of therespectively corresponding units of the CA 102.

The correspondence table between the reverse-charging service numbers ofthe reverse-charging service contractors and the called destinationtelephone numbers thereof is stored in thereverse-charging-service-number storage unit 311 beforehand. The feerate discrimination unit 312 has a database in which the IP fee rate andthe PSTN fee rate are stored in correspondence with the combinations ofcall originating terminals and call reception terminals, and itdiscriminates the fee rate in accordance with the sorts of the calloriginating terminal and the call reception terminal in the reversecharging service. The charged-party-business-company storage unit 313temporarily stores therein the information of a business company whichis altered to a charged party. The charging stop unit 314 stops thecharging of the exchanges on the call originating side and the calleddestination side. The reverse-charging control unit 302 controls thevarious functional blocks within the reverse-charging service controlapparatus 107.

Next, data formats will be described. FIG. 4 is a diagram showing anexample of a fee charging database which is included in the PSTNcharging management apparatus 108. The database contains charginginformation 402 which corresponds to the charged-party information 401of each call fee. In the database shown in FIG. 4, the telephone number401 of a PSTN subscriber being the charged party of a call fee, and thecharging information 402 indicating a total call fee up to the presenttime are registered at, for example, an entry 403-1. Registered at anentry 403-N are, for example, the charged-party information 401 of an IPbusiness company A being the charged party of the fee (for example, theidentification information of the IP business company A), and thecharging information 402 for charging a connection fee which arises whenthe PSTN side is connected to the IP network possessed by the IPbusiness company A. In this embodiment, in order to realize the reversecharging, the connection fee in the case of the connection from the PSTNside to the IP side is charged to the IP business company on the calleddestination side.

FIG. 5 is a diagram showing an example of a fee charging database whichis included in the IP charging management apparatus 110. The databasecontains charging information 502 which corresponds to the charged-partyinformation 501 of each call fee. In the database shown in FIG. 5, thetelephone number 501 of an IP telephone subscriber being the chargedparty of the call fee, and the charging information 502 being a totalcall fee up to the present time are registered at, for example, an entry503-1. Registered at an entry 503-N are the charged-party information501 of the PSTN side being the charged party of the fee (for example,the identification information of the PSTN business company), and thecharging information 502 for charging a connection fee which arises whenthe IP business company side is connected to the PSTN. In thisembodiment, in order to realize the reverse charging, the connection feein the case of the connection from the IP side to the PSTN is charged tothe PSTN business company on the called destination side, not to thecall originating side to which the connection fee is usually charged.FIG. 6 is a diagram showing a configurational example of a database forthe reverse charging service as is included in thereverse-charging-service-number storage unit 311 of the reverse-chargingservice control apparatus 107 for realizing the reverse charging servicewith the IP network. The database contains the called destinationtelephone numbers 602 of reverse-charging service contractors, and theidentification information items 604 of telephone business companieswith which the owners of called destination telephone terminalscontract, in correspondence with the reverse-charging service numbers601 of the reverse-charging service contractors.

The business company identification information 604 can also beregistered in case of registering anew the reverse-charging servicenumber 601 of a reverse-charging service contractor and the calleddestination telephone number 602 thereof. Alternatively, when thereverse-charging service number 601 of a reverse-charging servicecontractor and the called destination telephone number 602 thereof areregistered, the reverse-charging service control apparatus 107 canautomatically register the business company 604 on the basis of abusiness company number which is allocated to the several upper digitsof the telephone number.

In the database included in the reverse-charging-service-number storageunit 311, the reverse-charging service numbers 601 of PSTN subscribertelephone owners being the contractors of the reverse charging service,the called destination telephone numbers 602 of the reverse-chargingservice contractors, and a PSTN business company A with which thereverse-charging service contractors contract are registered at, forexample, entries 603-1 and 603-2. Besides, regarding an entry 603-N byway of example, there are registered the reverse-charging service number601 of an IP telephone owner. being the contractor of the reversecharging service, the called destination telephone number 602 of thereverse-charging service contractor, and an IP business company A withwhich the reverse-charging service contractor contracts.

FIG. 7 is a diagram showing a configurational example of a databasewhich is included in the routing-number discrimination unit 211 withinthe CA 102. The database contains a connection system 702 in whicheither ordinary calling connection or reverse charging connection isregistered in correspondence with, for example, a routing number 701. Inthe database shown in FIG. 7, at an entry 703-1 by way of example, “045”being the office number of a telephone number is registered in therouting number 701, and the ordinary calling connection is registered inthe connection system 702 because the registered number is not therouting number of the reverse charging service. Likewise, at an entry703-2, “050” being the telephone number of an IP telephone is registeredin the routing number 701, and the ordinary calling connection isregistered in the connection system 702 because the telephone numberregistered in the routing number 701 is not the routing number of thereverse charging service.

On the other hand, at an entry 703-N, “0120” being the routing number ofthe reverse charging service is registered in the routing number 701,and the reverse charging connection is registered in the connectionsystem 702 because the number “0120” indicates the reverse chargingservice. Incidentally, only the items concerning the reverse chargingservice may well be registered in the table, so as to judge the ordinarycalling connection in the nonexistence of a corresponding entry. FIG. 8is a diagram showing a configurational example of a database which isincluded in the IP-address storage unit 206 within the CA 102. Thedatabase contains the IP addresses 802 of called destinations incorrespondence with called destination telephone numbers 801. In thedatabase shown in FIG. 8, the called destination telephone numbers 801registered at, for example, entries 803-1 and 803-2 are the telephonenumbers of the subscribers of the PSTN, and the IP addresses 802 of theMGs 104 connected with the exchanges 106 accommodating PSTN subscribertelephones are registered at these entries beforehand. The calleddestination telephone number 801 registered at an entry 803-N is thetelephone number of an IP telephone subscriber, and the IP address 802of an IP telephone being the called destination is registered at thisentry beforehand.

FIG. 9 is a diagram showing a configurational example of a databasewhich is included in the terminal discrimination unit 303 within thereverse-charging service control apparatus 107. The database containsterminal types 902 indicating the sorts of terminals, in correspondencewith telephone numbers 901. Each telephone number 901 can be formed ofseveral upper digits (for example, a part corresponding to an officenumber) necessary for discriminating the terminal type, in the telephonenumber of a calling source or a called destination.

In the database shown in FIG. 9, an entry 903-1, for example, indicatesthat a PSTN subscriber telephone is registered in the terminal type 902in a case where the information of the telephone number is not stored inthe calling-source-telephone-number storage unit 307. The telephonenumbers 901 registered at entries 903-2 and 903-3 are toll numbers inPSTN subscriber telephones, and the terminal types 902 of these entriesindicate PSTN subscriber telephones. The telephone number 901 registeredat an entry 903-N is the telephone number of an IP telephone, and theterminal type 902 of this entry indicates the IP telephone.

FIG. 10 is a diagram showing a configurational example of the databaseof the fee-rate discrimination unit 312 within the reverse-chargingservice control apparatus 107. The database contains reverse-chargingservice contractor terminals 1001 in which the sorts of the terminals ofreverse-charging contractors are registered, and it contains PSTN feerates 1003 in which the fee rates of the PSTN side are registered, aswell as IP fee rates 1004 in which the fee rates of the IP network sideare registered, in correspondence with call originating terminals 1002in which the sorts of calling terminals, are registered.

In the database shown in FIG. 10, an entry 1005-1, for example, is anentry which indicates the PSTN fee rate 1003 and the IP fee rate 1004 inthe case where the terminal (called destination) of a reverse-chargingservice contractor is an IP telephone, and where a call originatingterminal that has originated a call to a reverse-charging service numberis an IP telephone. Incidentally, the PSTN fee rate may well be omittedin the combination of these terminals. Likewise, an entry 1005-2 is anentry which indicates the PSTN fee rate 1003 and the IP fee rate 1004 inthe case where the terminal of a reverse-charging service contractor isan IP telephone, and where a call originating terminal that hasoriginated a call to a reverse-charging service number is a PSTNsubscriber telephone. An entry 1005-3 is an entry which indicates thePSTN fee rate 1003 and the IP fee rate 1004 in the case where theterminal of a reverse-charging service contractor is a PSTN subscribertelephone, and where a call originating terminal that has originated acall to a reverse-charging service number is an IP telephone. An entry1005-N is an entry which indicates the PSTN fee rate 1003 and the IP feerate 1004 in the case where the terminal of a reverse-charging servicecontractor is a PSTN subscriber telephone, and where a call originatingterminal that has originated a call to a reverse-charging service numberis a PSTN subscriber telephone. Incidentally, the IP fee rate may wellbe omitted in the combination of these terminals.

Incidentally, although the fees based on 3 minutes are listed in FIG.10, appropriate fee rates can be registered without being restricted tothe list. Besides, in a case where pluralities of PSTN businesscompanies and IP business companies are existent, fee ratescorresponding to the combinations of the individual business companiescan be registered. Next, there will be described the operation of thereverse charging service which is based on call origination from an IPtelephone and call reception at the PSTN. More specifically, theoperation corresponds to a case where an IP telephone subscriberreceives the reverse charging service by originating a call from the IPtelephone to a PSTN subscriber telephone which is a reverse-chargingservice contractor.

FIG. 11 shows an example of the sequence of the reverse charging servicewhich is based on the call origination from the IP telephone and thecall reception at the PSTN subscriber telephone. FIGS. 12 and 13exemplify flow charts showing the operation of the CA 102 in the reversecharging service which is based on the call origination from the IPtelephone and the call reception at the PSTN subscriber telephone. FIG.14 exemplifies a flow chart showing the operation of thereverse-charging service control apparatus 107 in the reverse chargingservice which is based on the call origination from the IP telephone andthe call reception at the PSTN subscriber telephone. Now, the operationof the reverse charging service will be described with reference toFIGS. 11-14.

First, the IP telephone 101 originates the call with a reverse-chargingservice number (for example, a number for reverse charging as beginswith “0120”) toward the PSTN subscriber telephone 109 which is thereverse-charging service contractor (FIG. 11: 1101). The CA 102 detectsthe call origination of the IP telephone 101, and receives informationitems necessary for calling connection, such as a called destinationtelephone number (here, the reverse-charging service number) and acalling source telephone number (FIG. 12: 1201). By way of example, theSIP process unit 203 in the CA 102 detects the call origination andreceives the information through the IP-network interface 201. The CA102 judges whether or not the called destination telephone numberacquired is the routing number of the reverse charging service, by therouting-number discrimination unit 211 which is included in the CAitself (1202). Incidentally, processes and steps in the CA 102 arecontrolled or dealt with by the CA control unit 202. In a case where thecalled destination telephone number acquired is not the routing numberof the reverse charging service (1202), the CA 102 judges ordinarycalling connection and processes it (1203). On the other hand, in a casewhere the acquired number is the routing number of the reverse chargingservice (1202), the CA 102 transmits the reverse-charging service number601 and the calling source telephone number to the reverse-chargingservice control apparatus 107 through the common channel signalingnetwork 105 and inquires about the called destination telephone number602 of the reverse-charging service contractor (1102 and 1204).

The reverse-charging service control apparatus 107 (for example, thereverse-charging control unit 302, and the same will apply in theensuing description unless otherwise specified) receives thereverse-charging service number 601 and the calling source telephonenumber from the CA 102, and it stores the received calling sourcetelephone number in the calling-source-telephone-number storage unit 307(FIG. 14: 1301). Further, the reverse-charging service control apparatus107 examines the reverse-charging service numbers 601 registered in thedatabase of the reverse-charging-service-number storage unit 311included in the apparatus itself, on the basis of the receivedreverse-charging service number 601 (1302). In a case where thecorresponding number is not registered in the database (1303), thereverse-charging service control apparatus 107 transmits informationindicative of the non-registration to the CA1O2 (1304). On the otherhand, in a case where the corresponding number is registered (1303), thereverse-charging service control apparatus 107 acquires the calleddestination telephone number 602 and the business company identificationinformation 604 which correspond to the reverse-charging service number601 registered in the database, and it stores the called destinationtelephone number 602 in the called-destination-telephone-number storageunit 306 included in the apparatus itself and also stores the businesscompany identification information 604 in thecharged-party-business-company storage unit 313 (1305). Thereverse-charging service control apparatus 107 transmits an inquiryresult containing the acquired called-destination telephone number 602,to the CA 102 through the common channel signaling network 105 (1103 and1306).

The CA 102 (for example, the CA control unit 202, and the same willapply in the ensuing description unless otherwise specified) receivesthe result of the inquiry as contains the called destination telephonenumber 602 (1205). In a case where the CA 102 has received theinformation indicative of the non-registration, or where it has failedto acquire the called destination telephone number 602 within apredetermined time since the inquiry about the called destinationtelephone number (1206), the data of voice guidance is readout of thevoice-guidance sending unit 204 included in the CA 102, the data isconverted into voice packets by the voice-signal conversion unit 205,and the voice guidance is given forth to the IP telephone 101 being thecalling source (1207). On the other hand, in a case where the CA 102 hassucceeded in acquiring the called destination telephone number 602(1206), this CA 102 examines the called destination telephone numbers801 registered in the database of the IP-address storage unit 206included in the CA 102 itself, on the basis of the receivedcalled-destination telephone number 602 (1208). In a case where thecorresponding called-destination telephone number 801 is not registered(1209), the CA 102 gives forth the voice guidance to the IP telephone101 similarly to the above (1207). On the other hand, in a case wherethe corresponding called-destination telephone number 801 is registered(1209), the CA 102 acquires the IP address 802 corresponding to thecalled destination telephone number 801 (1210).

The CA 102 is connected with the exchange 106 accommodating the PSTNsubscriber telephone 109 of the reverse-charging service contractor,through the IP network 103 and the MG 104 indicated by the IP address,on the basis of the acquired IP address 802 and called destinationtelephone number 801 (1104 and 1211). The exchange 106 is connected withthe PSTN subscriber telephone 109 of the reverse-charging servicecontractor on the basis of the called destination telephone number 801,and it inquires IP telephonic communication is possible (1105). The PSTNsubscriber telephone 109 judges whether or not call reception ispossible, and it sends propriety information to the exchange 106 inreply (1106). The exchange 106 having received the information transmitsthe information to the CA 102 (1107). The CA 102 receives the proprietyinformation on the telephonic communication (1250). In a case where thereceived information is not information indicative of telephoniccommunicability (1212), the CA 102 transmits busy tone to the IPtelephone 101 (1108 and 1213). On the other hand, in a case where thereceived information indicates the telephonic communicability, the CA102 gives forth ringing tone to the IP telephone 101 (1108 and 1214).Besides, the CA 102 transmits information indicative of a ringing statusto the reverse-charging service control apparatus 107 (1109 and 1215).Incidentally, processes (for example, 1104 and 1108) concerning theconnection with the PSTN subscriber telephone can be executed inaccordance with a predetermined protocol by, for example, the SIPprocess unit 203.

Upon receiving the information indicative of the ringing status from theCA 102, the reverse-charging service control apparatus 107 transmits tothe CA 102 an alteration instruction which contains the telephone numberstored in the called-destination-telephone-number storage unit 306 andthe business company of the identification information 604 stored in thecharged-party-business-company storage unit 313, and which instructs theCA 102 to alter them to charged parties (1110 and 1307). Upon receivingthe alteration instruction, the CA 102 stores the telephone number andthe business company identification information which are contained inthe alteration instruction and which are to be altered to the chargedparty, in the charged-party management unit 213 (1216).

In order to give a fee-rate alteration instruction, the reverse-chargingservice control apparatus 107 reads out the telephone number stored inthe calling-source-telephone-number storage unit 307, and it examinesthe read-out telephone number and discriminates the terminal type 902 ofthe call originating terminal on the basis of the telephone number 901by the terminal discrimination unit 303 included in the apparatusitself. Besides, the reverse-charging service control apparatus 107similarly discriminates the terminal type of the reverse-chargingservice contractor terminal (call reception terminal) as to thetelephone number 602 stored in the called-destination-telephone-numberstorage unit 306. On the basis of the discriminated terminal types, thereverse-charging service control apparatus 107 discriminates that entryof the database of the fee-rate discrimination unit 312 in which thepertinent service contractor terminal and call originating terminalagree with the information items of the reverse-charging servicecontractor terminal 1001 and call originating terminal 1002,respectively, so as to acquire the corresponding PSTN fee rate and IPfee rate. Besides, the reverse-charging service control apparatus 107transmits the alteration instruction containing the acquired IP fee rate1004, to the CA 102 (1111 and 1308). The CA 102 receives the alterationinstruction containing the IP fee rate, and stores the IP fee rate inthe database of the fee-rate management unit 209 (1217). Besides, thereverse-charging service control apparatus 107 stores the acquired PSTNfee rate 1003 in the fee-rate management unit 309 (1308).

The reverse-charging service control apparatus 107 (for example, thecharging stop unit 314) causes the exchange 106 (exchange connected atthe step 1104), which accommodates the PSTN subscriber telephone 109being the reverse-charging service contractor, to stop charging to theIP business company (1112 and 1309). Usually, in the connection from theIP business company (IP telephone) to the exchange 106, this exchange106 charges a fee for the connection thereto and demands payment fromthe IP business company. In this embodiment, however, the charging ofthe exchange to the IP business company needs to be stopped forperforming the reverse charging, that is, for charging to the PSTN side.This embodiment consists, for example, in that the charging by theexchange on the call reception side is stopped so as to charge the feeby the reverse-charging service control apparatus 107, and that thecharged party is altered to the called destination telephone number inthe charging of the call originating side.

When the handset of the PSTN subscriber telephone 109 has been taken up,this PSTN subscriber telephone 109 being the reverse-charging servicecontractor transmits information indicative of the establishment of atelephonically communicable status to the exchange 106 (1113). Theexchange 106 receives the information, and transmits informationindicative of telephonic communicability to the CA 102 (1114). The CA102 receives the information, and transmits this information to thereverse-charging service control apparatus 107 (1115 and 1218). Besides,the CA 102 having received the information starts the monitoring of atalking time by the time monitoring unit 208 (1219). Besides, thereverse-charging service control apparatus 107 having received theinformation starts the monitoring of the talking time by the timemonitoring unit 308 (1310).

The CA 102 (for example, the SIP process unit 203) transmits theinformation indicative of the telephonic communicability to the IPtelephone 101 (1116). Thus, the telephonic communication between the IPtelephone 101 and the PSTN subscriber telephone 109 is permitted.Further, the CA 102 acknowledges the reception of the information to theexchange 106 (1117), and it continues the monitoring of the talking timeuntil either of the IP telephone 101 and the PSTN subscriber telephone109 being the reverse-charging service contractor disconnects a line.

Here, a case where the PSTN subscriber telephone 109 has disconnectedthe line will be described by way of example. When the handset of thePSTN subscriber telephone 109 has been put back to disconnect the line,information indicative of the disconnection is transmitted from the PSTNsubscriber telephone 109 to the exchange 106 (1118). The exchange 106receives the information and transmits information indicative of thedisconnection to the CA 102 (1119), whereupon the CA 102 receives theinformation and transmits this information to the reverse-chargingservice control apparatus 107 (1120 and 1220). Besides, the CA 102having received the information ends the monitoring of the talking timeby the time monitoring unit 208 (1221). Likewise, the reverse-chargingservice control apparatus 107 having received the information ends themonitoring of the talking time by the time monitoring unit 308 (1311).Further, the CA 102 transmits information indicative of thedisconnection of the line to the IP telephone 101 (1121), and itacknowledges the disconnection to the exchange 106 (1122). When thehandset of the IP telephone 101 has been put back, informationindicative of the disconnection is transmitted from the IP telephone 101to the CA 102 (1123).

After the telephonic communication has ended, the fee calculation unit210 of the CA 102 calculates a fee (charging information) on the basisof the talking time monitored by the time monitoring unit 208, and theIP fee rate stored in the fee-rate management unit 209. Further, it setsthe telephone business company (here, the PSTN business company A)stored in the charged-party management unit 213, as a charged party, andit generates first fee information which contains the charged party andthe charging information (1222). Besides, the fee calculation unit 210sets the called destination telephone number of the reverse-chargingservice contractor as stored in the charged-party management unit 213,as a charged party, and it generates second fee information whichcontains the charged party and the calculated fee information (1222). Inthis manner, the fee calculation unit 210 generates the two kinds of feeinformation which have the different charged parties. Incidentally, thefees calculated here are the fees of the IP network side, and they donot contain any fee of the PSTN side (for example, a connection feeinvolved between the business sites of the exchange and the MG).

The CA 102 transmits to the IP charging management apparatus 110 (calloriginating side) the first fee information in which the telephonebusiness company of the reverse-charging service contractor is set asthe charged party (1124 and 1223). The IP charging management apparatus110 receives the first fee information, it examines the charged partyinformation 501 of the database included in the apparatus itself, on thebasis of the information set as the charged party, and it adds thecharging information contained in the first fee information, to thecharging information 502 corresponding to the pertinent charged partyinformation 501. By way of example, in the exemplary database shown inFIG. 5, the charging information contained in the first fee informationis added to the charging information of the entry 503-N. Incidentally, atotal fee up to the last telephone call is charged in the charginginformation 502, and a bill is managed by adding the charginginformation 502 received anew.

Further, the CA 102 transmits the second fee information in which thecalled destination telephone number of the reverse-charging servicecontractor is set as the charged party (1126), to the PSTN chargingmanagement apparatus 108 (call reception side) via, for example, thereverse-charging service control apparatus 107 (1125 and 1223). The PSTNcharging management apparatus 108 receives the second fee information,it examines the charged party information 401 of the database includedin the apparatus itself, on the basis of the information set as thecharged party, and it adds the charging information contained in thesecond fee information, to the charging information 402 corresponding tothe pertinent charged party information 401, thereby to manage a bill.By way of example, in the exemplary database shown in FIG. 4, thecharging information contained in the second fee information is added tothe charging information of the entry 403-1.

The fee calculation unit 310 of the reverse-charging service controlapparatus 107 calculates a fee (charging information) on the basis ofthe talking time monitored by the time monitoring unit 308, and the PSTNfee rate stored in the fee-rate management unit 309. It generates thirdfee information in which the called destination telephone number of thereverse-charging service contractor as stored in thecalled-destination-telephone-number storage unit 206 is set as a chargedparty (1312). The reverse-charging service control apparatus 107transmits the generated third fee information to the PSTN chargingmanagement apparatus 108 (call reception side) (1127 and 1313). The PSTNcharging management apparatus 108 receives the third fee information, itexamines the charged party information 401 of the database included inthe apparatus itself, on the basis of the information set as the chargedparty, and it adds the charging information contained in the third feeinformation, to the charging information 402 corresponding to thepertinent charged party information 401, thereby to manage a bill. Byway of example, in the exemplary database shown in FIG. 4, the charginginformation contained in the third fee information is added to thecharging information of the entry 403-1. Accordingly, the fee of the IPside and that of the PSTN side are added up and charged to the PSTNsubscriber telephone being the called destination, as thus fardescribed.

Owing to the above operation, the reverse charging service can beprovided in the case where the IP telephone subscriber has originatedthe call to the PSTN subscriber telephone being the reverse-chargingservice contractor. Incidentally, the PSTN business company demands thepayment of the sum between the fee of the IP network and that of thePSTN network, from the PSTN subscriber telephone 109 in accordance withthe fee information stored in the PSTN charging management apparatus108, while the IP business company demands the payment of the fee of theIP network from the PSTN business company in accordance with the feeinformation stored in the IP charging management apparatus 110.

Next, there will be described the operation of the reverse chargingservice which is based on call origination from a PSTN telephone andcall reception at an IP telephone. More specifically, the operationcorresponds to a case where a PSTN subscriber receives the reversecharging service by originating a call to the IP telephone which is areverse-charging service contractor. FIG. 15 shows an example of thesequence of the reverse charging service which is based on the callorigination from the PSTN subscriber telephone. FIG. 16 exemplifies aflow chart showing the operation of the CA 102 in the reverse chargingservice which is based on the call origination from the PSTN subscribertelephone. FIG. 17 exemplifies a flow chart showing the operation of thereverse-charging service control apparatus 107 in the reverse chargingservice which is based on the call origination from the PSTN subscribertelephone. Now, the operation of the reverse charging service will bedescribed with reference to FIGS. 15-17.

First, the PSTN subscriber telephone 109 originates the call with areverse-charging service number toward the IP telephone 101 which is thereverse-charging service contractor (FIG. 15: 1401). The exchange 106detects the call origination of the PSTN subscriber telephone 109, andreceives information items necessary for calling connection, such as acalled destination telephone number (here, the reverse-charging servicenumber) and a calling source telephone number. The exchange 106 decideswhether the called destination telephone number received is thereverse-charging service number or the number of ordinary callorigination. In case of the reverse-charging service number, theexchange 106 transmits the reverse-charging service number and thecalling source telephone number to the reverse-charging service controlapparatus 107 and inquires about the called destination telephone numberof the reverse-charging service contractor (1402).

The reverse-charging service control apparatus 107 receives thereverse-charging service number and the calling source telephone numberfrom the exchange 106, and stores the received calling-source telephonenumber in the calling-source-telephone-number storage unit 307 (FIG. 17:1600). Further, the reverse-charging service control apparatus 107examines the reverse-charging service numbers 601 registered in thedatabase of the reverse-charging-service-number storage unit 311included in the apparatus itself, on the basis of the receivedreverse-charging service number 601 (1601). In a case where thecorresponding number is not registered (1602), the reverse-chargingservice control apparatus 107 transmits information indicative of thenon-registration to the exchange 106 (1603). On the other hand, in acase where the corresponding number is registered (1602), thereverse-charging service control apparatus 107 acquires the calleddestination telephone number 602 and the business company identificationinformation 604 which correspond to the reverse-charging service number601 registered in the database, and it stores the called destinationtelephone number 602 in the called-destination-telephone number storageunit 306 included in the apparatus itself and also stores the businesscompany identification information 604 in thecharged-party-business-company storage unit 313 (1604). Thereverse-charging service control apparatus 107 transmits an inquiryresult containing the acquired called-destination telephone number 602,to the exchange 106 through the common channel signaling network 105(1403 and 1605). Besides, the reverse-charging service control apparatus107 (for example, the charging stop unit 314) instructs the exchange 106to bring the charging status of the PSTN subscriber telephone 109 beingthe call originator, into the non-charging status thereof (1404 and1606).

The exchange 106 receives the result of the inquiry as contains thecalled destination telephone number 602. By way of example, in a casewhere the exchange 106 has acquired the information indicative of thenon-registration, or where it has failed to acquire the calleddestination telephone number 602 within a predetermined time since theinquiry about the called destination telephone number, it gives forththe predetermined voice guidance to the PSTN subscriber telephone 109.

Subsequently, the exchange 106 transmits the received called-destinationtelephone number 602 to the CA 102 (1405). The CA 102 examines thecalled destination telephone numbers 801 registered in the database ofthe IP-address storage unit 206 included in the CA 102 itself, on thebasis of the called destination telephone number 602 received (FIG. 16:1501). In a case where the pertinent called destination telephone number801 is not registered (1502), the CA 102 sends information indicative ofnon-connectability to the exchange 106 in reply (1503). On the otherhand, in a case where the pertinent called destination telephone number801 is registered, the CA 102 acquires the IP address 802 correspondingto the called destination telephone number 801. Then, the CA 102 isconnected with the IP telephone 101 being the reverse-charging servicecontractor, through the IP network 103 on the basis of the acquired IPaddress 802 (1504), and it inquires as to IP the IP telephone 101 istelephonically communicable (1406). The IP telephone 101 judges whetheror not the call reception is possible. By way of example, in a casewhere the IP telephone 101 is busy, it sends information indicative of abusy status to the CA 102 in reply. On the other hand, in a case wherethe telephonic communication is possible, the IP telephone 101 sendsinformation indicative of a ringing status in reply (1407).

The CA 102 receives an inquiry result which indicates whether or not thetelephonic communication is possible (1550). In a case where thereceived inquiry information is the information indicative of the busystatus, the CA 102 transmits information indicative of the busy statusto the exchange 106 through the common channel signaling network 105(1506). On the other hand, in a case where the CA 102 has received theinformation indicative of the ringing status, it transmits informationindicative of the ringing status to the exchange 106 through the commonchannel signaling network 105 (1408 and 1507). The exchange 106 havingreceived the information transmits information indicative of the ringingstatus to the reverse-charging service control apparatus 107 and thePSTN subscriber telephone 109 (1409 and 1410).

Besides, upon receiving the information indicative of the ringingstatus, the reverse-charging service control apparatus 107 transmits tothe CA 102 an alteration instruction which contains the calleddestination telephone number stored in thecalled-destination-telephone-number storage unit 306, and whichinstructs the CA 102 to alter the number to a charged party (1411 and1607). Upon receiving the alteration instruction, the CA 102 stores thecalled destination telephone number which is contained in the alterationinstruction and which is to be altered to the charged party, in thecharged-party management unit 213 (1508).

In order to give a fee-rate alteration instruction, the reverse-chargingservice control apparatus 107 reads out the calling source telephonenumber stored in the calling-source-telephone-number storage unit 307,and it examines the read-out calling-source telephone number anddiscriminates the terminal type 902 of the call originating terminal onthe basis of the telephone number 901 by the terminal discriminationunit 303 included in the apparatus itself. Besides, the reverse-chargingservice control apparatus 107 similarly discriminates the terminal typeof the call reception terminal as to the called destination telephonenumber 801 stored in the called-destination-telephone-number storageunit 306. On the basis of the discriminated terminal types, thereverse-charging service control apparatus 107 searches for that entryof the database of the fee-rate discrimination unit 312 in which thepertinent call reception terminal and call originating terminal agreewith the information items of the reverse-charging service contractorterminal 1001 and call originating terminal 1002, respectively, so as toacquire the corresponding PSTN fee rate and IP fee rate. Thereverse-charging service control apparatus 107 transmits the alterationinstruction containing the acquired PSTN fee rate 1003 and IP fee rate1004, to the CA 102 (1412 and 1608). Besides, the reverse-chargingservice control apparatus 107 stores the acquired PSTN fee rate 1003 inthe fee-rate management unit 309. The CA 102 receives the alterationinstruction containing the fee rates, and registers the received PSTNfee rate 1003 and IP fee rate 1004 in the database of the fee-ratemanagement unit 209 (1509).

When the handset of the IP telephone 101 has been taken up, this IPtelephone 101 being the reverse-charging service contractor transmitsinformation indicative of the establishment of a telephonicallycommunicable status to the CA 102 (1413). The CA 102 receives theinformation indicative of the telephonic communicability, and transmitssimilar information to the exchange 106 (1414 and 1510). The exchange106 receives the information, and transmits information indicative ofthe telephonic communicability to the reverse-charging service controlapparatus 107 and the PSTN subscriber telephone 109 (1415 and 1416).Thus, the telephonic communication between the PSTN subscriber telephone109 and the IP telephone 101 is permitted.

Upon receiving the information indicative of the telephoniccommunicability, the CA 102 starts the monitoring of a talking time bythe time monitoring unit 208 (1511). Besides, the reverse-chargingservice control apparatus 107 receives the information indicative of thetelephonic communicability from the exchange 106, and it starts themonitoring of the talking time by the time monitoring unit 308 (1609).Further, the exchange 106 acknowledges the reception of the informationto the CA 102 (1417), and it continues the monitoring of the talkingtime until either of the PSTN subscriber telephone 109 and the IPtelephone 101 being the reverse-charging service contractor disconnectsa line.

Here, a case where the IP telephone 101 has disconnected the line willbe described by way of example. When the handset of the IP telephone 101has been put back to disconnect the line, information indicative of thedisconnection is transmitted from the IP telephone 101 to the CA 102(1418). The CA 102 receives the information and transmits informationindicative of the disconnection of the line to the exchange 106 (1419and 1512). The exchange 106 receives the information and transmits thisinformation to the reverse-charging service control apparatus 107(1420). Besides, the CA 102 having received the information ends themonitoring of the talking time by the time monitoring unit 208 (1513).Likewise, the reverse-charging service control apparatus 107 havingreceived the information indicative of the disconnection of the lineends the monitoring of the talking time by the time monitoring unit 308(1610). Further, the exchange 106 transmits information indicative ofthe disconnection of the line to the PSTN subscriber telephone 109(1421). Besides, the exchange 106 acknowledges the disconnection to theCA 102 (1422). When the handset of the PSTN subscriber telephone 109 hasbeen put back, information indicative of the disconnection istransmitted from the PSTN subscriber telephone 109 to the exchange 106(1423).

After the telephonic communication has ended, the fee calculation unit210 of the CA 102 calculates a fee (charging information) on the basisof the talking time monitored by the time monitoring unit 208, and theIP fee rate and PSTN fee rate stored in the fee-rate management unit209. Further, it sets the called destination telephone number stored inthe charged-party management unit 213, as a charged party, and itgenerates fourth fee information which contains the charged party andthe charging information (1514). The CA 102 transmits the fourth feeinformation to the IP charging management apparatus 110 (1424 and 1515).The IP charging management apparatus 110 receives the fourth feeinformation, it examines the charged party information 501 of thedatabase included in the apparatus itself, on the basis of theinformation set as the charged party, and it adds the charginginformation contained in the fourth fee information, to the charginginformation 502 corresponding to the pertinent charged party information501, thereby to manage a bill.

Besides, the fee calculation unit 310 of the reverse-charging servicecontrol apparatus 107 calculates a fee (charging information) on thebasis of the talking time monitored by the time monitoring unit 308, andthe PSTN fee rate stored in the fee-rate management unit 309. Itgenerates fifth fee information in which the business company of theidentification information (here, the IP business company A) as storedin the charged-party-business-company storage unit 313 is set as acharged party, and which contains the charged party and the charginginformation (1611). The reverse-charging service control apparatus 107transmits the fifth fee information to the PSTN charging managementapparatus 108 (1425 and 1612). The PSTN charging management apparatus108 receives the fifth fee information, it examines the charged partyinformation 401 of the database included in the apparatus itself, on thebasis of the information set as the charged party, and it adds thecharging information contained in the fifth fee information, to thecharging information 402 corresponding to the pertinent charged partyinformation 401, thereby to manage a bill.

Owing to the above, the reverse charging service can be realized even inthe case where the owner of the PSTN subscriber telephone has originatedthe call to the IP telephone being the reverse-charging servicecontractor. Incidentally, the PSTN business company demands the paymentof the fee of the PSTN network from the IP business company inaccordance with the fee information stored in the PSTN chargingmanagement apparatus 108, while the IP business company demands thepayment of the sum between the fee of the IP network and that of thePSTN network, from the IP subscriber telephone 101 in accordance withthe fee information stored in the IP charging management apparatus 110.

Next, a different embodiment for the creation of fee information will bedescribed. Apart from the methods described above, the CA 102 and thereverse-charging service control apparatus 107 canappropriately-generate and transmit fee information. More specifically,the reverse-charging service control apparatus 107 and the call agent102 are allowed to generate fee information on the basis of a talkingtime and fee rates so that the sum of fees in the IP network and thepublic switching telephone network may be charged to a calleddestination telephone number which is stored in thecalled-destination-telephone-number storage unit 306 and thecharged-party management unit 213, and they are allowed to transmit thegenerated fee information to the charging management apparatus which thebusiness company (for example, PSTN business company) on a callreception side manages. In addition, the reverse-charging servicecontrol apparatus 107 and the call agent 102 are allowed to generate feeinformation so that a fee in the network on the side of a calloriginating terminal (for example, IP telephone) maybe charged to thebusiness company of the business company identification information of acalled destination which is stored in the charged-party-business-companystorage unit 313 and/or the charged-party management unit 213, and theyare allowed to transmit the generated fee information to the chargingmanagement apparatus which the business company (for example, IPbusiness company) of a calling source manages.

It is also allowed, for example, to stop the charging operations of theexchange 106 and the CA 102, and to generate all fee information itemsby the reverse-charging service control apparatus 107. Now, the casewhere the reverse-charging service control apparatus 107 generates allthe fee information items will be described by taking as an example thecase of call origination from an IP telephone and call reception at aPSTN subscriber telephone. In stopping the charging of the exchange 106,the reverse-charging service control apparatus 107 stops also thecharging of the CA 102. The other processes which are executed since thecall origination till the end of telephonic communication are the sameas in the foregoing, and shall be omitted from description.

After the telephonic communication has ended, the fee calculation unit310 of the reverse-charging service control apparatus 107 calculates afee (charging information) on the basis of the talking time monitored bythe time monitoring unit 308, and the IP fee rate stored in the fee-ratemanagement unit 309. Further, it sets the business company of thebusiness company identification information (here, PSTN business companyA) stored in the charged-party management unit 313, as a charged party,and it generates fee information which contains the charged party andthe charging information (corresponding to the step 1222). Thereverse-charging service control apparatus 107 transmits the generatedfee information to the IP charging management apparatus 110 (callorigination side) (corresponding to the steps 1124 and 1223). The IPcharging management apparatus 110 receives the fee information, and itadds the charging information to the corresponding entry as in theforegoing.

Further, the fee calculation unit 310 of the reverse-charging servicecontrol apparatus 107 calculates the sum of fees (charging informationitems) in the IP network and the PSTN on the basis of the talking timemonitored by the time monitoring unit 308, as well as the IP fee ratestored in the fee-rate management unit 309, and the talking time as wellas the PSTN fee rate, whereupon it generates fee information in whichthe called destination telephone number of the reverse-charging servicecontractor stored in the called-destination-telephone-number storageunit 206 is set as a charged party (corresponding to the step 1312).Incidentally, the IP fee rate and the PSTN fee rate which have beendiscriminated by the fee-rate discrimination unit 312 are stored in thefee-rate management unit 309 beforehand. By way of example, they arestored at the step 1308 stated before. The reverse-charging servicecontrol apparatus 107 transmits the generated fee information to thecharging management apparatus (here, PSTN charging management apparatus108) which corresponds to the business company identificationinformation stored in the charged-party-business-company storage unit313 (corresponding to the steps 1127 and 1313). The PSTN chargingmanagement apparatus 108 receives the fee information, and it adds thecharging information 402 to the corresponding entry as in the foregoing.

In this manner, according to the present invention, it is possible toprovide the reverse charging service directed from the IP telephone tothe PSTN subscriber telephone. Accordingly, telephone calls through theIP networks which are generally inexpensive become possible, and thereverse-charging service contractors of the PSTN can provide reversecharging services without caring about the call fees of reception callsfrom very long distances. Moreover, according to the present invention,it is possible to provide reverse charging services which are directedfrom a PSTN subscriber telephone and an IP telephone to IP telephonesubscribers, and which have hitherto been unavailable.

1. In a telephone network wherein an IP telephone set connected to an IPnetwork, and a public switching telephone set connected to an exchangecan be interconnected through a media gateway which connects the IPnetwork and the exchange; a reverse charging system comprising: a callagent which communicates information with an IP charging managementapparatus for the IP telephone set, which communicates control signalswith a public switching telephone network, and which performs a callcontrol in connection with the IP network; and a reverse-chargingservice control apparatus which communicates information with a PSTNcharging management apparatus for the public switching telephone set andwith the IP charging management apparatus, and which communicates withsaid call agent and said exchange, thereby to perform a callingconnection control of a reverse charging service; said call agentincluding: an IP-address storage unit in which an IP address of themedia gateway for connecting with said exchange that accommodates thepublic switching telephone set of a called destination, or an IP addressof the IP telephone set of a called destination is stored incorrespondence with a called destination telephone number beforehand; afirst time monitoring unit which monitors a talking time between the IPtelephone set and the public switching telephone set; and a first feecalculation unit which calculates charging information on the basis ofthe talking time monitored by said first time monitoring unit, and an IPfee rate indicating a fee per predetermined time in the IP network,and/or a PSTN fee rate indicating a fee per predetermined time in thepublic switching telephone network, and which generates fee informationthat contains charged party information and the calculated charginginformation; said reverse-charging service control apparatus including:a reverse-charging-service-number storage unit in which the calleddestination telephone number and business company identificationinformation of the called destination are stored in correspondence withreverse-charging service number for the reverse charging servicebeforehand; a second time monitoring unit which monitors a talking timebetween the IP telephone set and the public switching telephone set; anda second fee calculation unit which calculates charging information onthe basis of the talking time monitored by said second time monitoringunit, and the IP fee rate and/or the PSTN fee rate, and which generatesfee information that contains charged party information and thecalculated charging information; wherein said call agent or saidexchange detects corresponding call origination from the IP telephoneset or the public switching telephone set respectively, receives thereverse-charging service number, and transmits the receivedreverse-charging service number to said reverse-charging service controlapparatus; said reverse-charging service control apparatus receives thereverse-charging service number, and acquires the called destinationtelephone number and the business company identification information ofthe called destination as correspond to the received reverse-chargingservice number, with reference to said reverse-charging-service-numberstorage unit; said reverse-charging service control apparatus sends theacquired called-destination telephone number and/or the acquiredbusiness-company identification information of the called destination tosaid call agent or said exchange in reply; said call agent receives thecalled destination telephone number from said reverse-charging servicecontrol apparatus or said exchange, acquires the IP addresscorresponding to the received called-destination telephone number withreference to said IP-address storage unit, and connects the IP telephoneset and the public switching telephone set on the basis of the acquiredIP address; said reverse-charging service control apparatus causes saidexchange that accommodates the public switching telephone set, to stopcharging; said first fee calculation unit of said call agent and saidsecond fee calculation unit of said reverse-charging service controlapparatus calculate the charging information on the basis of the talkingtimes monitored by the first and second time monitoring units, and theIP fee rate and/or the PSTN fee rate, respectively; and said first feecalculation unit of said call agent and said second fee calculation unitof said reverse-charging service control apparatus generate the feeinformation by setting the charged party information so that a sum offees in the IP network and the public switching telephone network may becharged to the called destination telephone number, transmits thegenerated fee information to the IP charging management apparatus or thePSTN charging management apparatus on a called destination side, and,they generate the fee information by setting the charged partyinformation so that a fee in the network on a call origination side maybe charged to a business company of the business company identificationinformation of the called destination, transmits the generated feeinformation to said IP charging management apparatus or said PSTNcharging management apparatus on the call origination side.
 2. A reversecharging system according to claim 1, wherein: a telephone set of thecalling source is the IP telephone set, and, a telephone set of thecalled destination is the public switching telephone set; said callagent receives the called destination telephone number and the businesscompany identification information of the called destination sent fromsaid reverse-charging service control apparatus in reply; said first feecalculation unit of said call agent calculates first charginginformation on the basis of the talking time monitored by said firsttime monitoring unit, and the IP fee rate, and sets the receivedbusiness company identification information of the called destination asthe charged party information, so as to generate first fee informationthat contains the charged party information and the first charginginformation, and to transmit the first fee information to said IPcharging management apparatus, and, it sets the receivedcalled-destination telephone number as the charged party information, soas to generate second fee information that contains the charged partyinformation and the first charging information, and to transmit thesecond fee information to said PSTN charging management apparatus; andsaid second fee calculation unit of said reverse-charging servicecontrol apparatus calculates second charging information on the basis ofthe talking time monitored by said second time monitoring unit and thePSTN fee rate, and sets the called destination telephone number as thecharged party information, so as to generate third fee information thatcontains the charged party information and the second charginginformation, and to transmit the third fee information to said PSTNcharging management apparatus.
 3. A reverse charging system according toclaim 1, wherein: a telephone set of the calling source is the publicswitching telephone set, and, a telephone set of the called destinationis the IP telephone set; said first fee calculation unit of said callagent calculates third charging information that contains the fees inthe IP network and the public switching telephone network, on the basisof the talking time monitored by said first time monitoring unit and theIP fee rate and the PSTN fee rate, and sets the receivedcalled-destination telephone number as the charged party information, soas to generate fourth fee information that contains the charged partyinformation and the third charging information, and to transmit thefourth fee information to said IP charging management apparatus; andsaid second fee calculation unit of said reverse-charging servicecontrol apparatus calculates fourth charging information on the basis ofthe talking time monitored by said second time monitoring unit and thePSTN fee rate, and sets the acquired business-company identificationinformation of the called destination as the charged party information,so as to generate fifth fee information that contains the charged partyinformation and the fourth charging information, and to transmit thefifth fee information to said PSTN charging management apparatus.
 4. Areverse charging system according to claim 1, wherein: saidreverse-charging service control apparatus further includes: a terminaldiscrimination unit which has a database stored terminal typesindicating whether telephone sets are IP telephone sets or publicswitching telephone sets in correspondence with respective telephonenumbers, and which discriminates the terminal types of the telephonesets of the calling source and the called destination on the basis ofthe telephone numbers; and a fee-rate discrimination unit which has adatabase previously stored IP fee rates and PSTN fee rates incorrespondence with combinations between the terminal types of callingsource and called destination, and which acquires the IP fee rate andthe PSTN fee rate on the basis of the terminal types discriminated bysaid terminal discrimination unit; said call agent or said exchangefurther receive a calling source telephone number from the IP telephoneset or the public switching telephone set of the calling source whendetects the call origination, and transmit the received calling-sourcetelephone number to said reverse-charging service control apparatus;said reverse-charging service control apparatus receives the callingsource telephone number, and acquires the IP fee rate and the PSTN feerate by said terminal discrimination unit and said fee-ratediscrimination unit, on the basis of the received calling sourcetelephone number and the acquired called destination telephone number;said reverse-charging service control apparatus transmits the acquiredIP fee rate and/or PSTN fee rate to said call agent; and said first feecalculation unit of said call agent and said second fee calculation unitof said reverse-charging service control apparatus calculate thecharging information with the acquired IP fee rate and/or PSTN fee rate.5. A reverse charging system according to claim 1, wherein: said callagent further includes a routing-number discrimination unit which judgesif the telephone number of the called destination as has been receivedfrom the IP telephone set contains a routing number for the reversecharging; and when the routing number for the reverse charging iscontained, said call agent transmits the received reverse-chargingservice number and/or a calling source telephone number to saidreverse-charging service control apparatus, whereas when the routingnumber for the reverse charging is not contained, said call agentperforms an ordinary call control.
 6. A reverse-charging service controlapparatus in a reverse charging system which is applied to a telephonenetwork wherein an IP telephone set connected to an IP network, and apublic switching telephone set connected to an exchange can beinterconnected through a media gateway that connects the IP networks andthe exchange, and which has a call agent that communicates informationwith an IP charging management apparatus for the IP telephone set, thatcommunicates control signals with a public switching telephone network,and that performs a call control in connection with the IP network, andthe reverse-charging service control apparatus that communicatesinformation with a PSTN charging management apparatus for the publicswitching telephone set and with the IP charging management apparatus,and that communicates with the call agent and the exchange, thereby toperform a calling connection control of a reverse charging service; saidreverse-charging service control apparatus comprising: areverse-charging-service-number storage unit in which called destinationtelephone numbers and business company identification information ofcalled destinations are stored in correspondence with reverse-chargingservice numbers for the reverse charging service beforehand; a timemonitoring unit which monitors a talking time between the IP telephoneset and the public switching telephone set; and a fee calculation unitwhich calculates charging information on the basis of the talking timemonitored by said time monitoring unit, and an IP fee rate indicating afee per predetermined time in the IP network, and/or a PSTN fee rateindicating a fee per predetermined time in the public switchingtelephone network, and which generates fee information that containscharged party information and the calculated charging information;wherein said reverse-charging service control apparatus receives thereverse-charging service number from said call agent or said exchange,and acquires the called destination telephone number and the businesscompany identification information of the called destination ascorrespond to the received reverse-charging service number, withreference to said reverse-charging-service-number storage unit; saidreverse-charging service control apparatus sends the acquiredcalled-destination telephone number and/or the acquired business-companyidentification information of the called destination to said call agentor said exchange in reply; said reverse-charging service controlapparatus causes said exchange that accommodates the public switchingtelephone set, to stop charging; said fee calculation unit of saidreverse-charging service control apparatus calculates the charginginformation on the basis of the talking time monitored by said timemonitoring unit, and the IP fee rate and/or the PSTN fee rate; and saidfee calculation unit of said reverse-charging service control apparatusgenerates fee information by setting the charged party information sothat a sum of fees in the IP network and the public switching telephonenetwork may be charged to the called destination telephone number, usingfee information generated by said call agent on the basis of a talkingtime and a fee rate, and the fee information generated by said feecalculation unit on the basis of the talking time and the fee rate, soas to transmit the generated fee information to said IP chargingmanagement apparatus or said PSTN charging management apparatus on acalled destination side, and, generates fee information by setting thecharged party information so that a fee in the network on a callorigination side may be charged to a business company of the businesscompany identification information of the called destination, so as totransmit the generated fee information to said IP charging managementapparatus or said PSTN charging management apparatus on the callorigination side.
 7. A call agent in a reverse charging system which isapplied to a telephone network wherein an IP telephone set connected toan IP network, and a public switching telephone set connected to anexchange can be interconnected through a media gateway that connects theIP network and the exchange and which has the call agent thatcommunicates information with an IP charging management apparatus forthe IP telephone set, that communicates control signals with a publicswitching telephone network and that performs a call control inconnection with the IP network, and a reverse-charging service controlapparatus that communicates information with a PSTN charging managementapparatus for the public switching telephone set and with the IPcharging management apparatus, and that communicates with the call agentand the exchange, thereby to perform a calling connection control of areverse charging service; said call agent comprising: an IP-addressstorage unit in which an IP address of the media gateway for connectingwith said exchange that accommodates the public switching telephone setof a called destination, or an IP address of the IP telephone set of acalled destination is stored in correspondence with a called destinationtelephone number beforehand; a time monitoring unit which monitors atalking time between the IP telephone set and the public switchingtelephone set; and a fee calculation unit which calculates charginginformation on the basis of the talking time monitored by said timemonitoring unit, and an IP fee rate indicating a fee per predeterminedtime in the IP network, and/or a PSTN fee rate indicating a fee perpredetermined time in the public switching telephone network, and whichgenerates fee information that contains charged party information andthe calculated charging information; wherein said call agent detectscall origination from the IP telephone set, receives a reverse-chargingservice number, and transmits the received reverse-charging servicenumber to said reverse-charging service control apparatus; said callagent receives the called destination telephone number corresponding tothe reverse-charging service number from said reverse-charging servicecontrol apparatus or said exchange, acquires the IP addresscorresponding to the received called-destination telephone number withreference to said IP-address storage unit, and connects the IP telephoneset and the public switching telephone set on the basis of the acquiredIP address; said fee calculation unit of said call agent calculates thecharging information on the basis of the talking time monitored by saidtime monitoring unit, and the IP fee rate and/or the PSTN fee rate; andsaid fee calculation unit of said call agent generates fee informationby setting the charged party information so that a sum of fees in the IPnetwork and the public switching telephone network may be charged to thecalled destination telephone number, using fee information generated bysaid reverse-charging service control apparatus on the basis of atalking time and a fee rate, and the fee information generated by saidfee calculation unit on the basis of the talking time and the fee rate,so as to transmit the generated fee information to said IP chargingmanagement apparatus or said PSTN charging management apparatus on acalled destination side, and, generates fee information by setting thecharged party information so that a fee in the network on a callorigination side may be charged to a business company of the businesscompany identification information of the called destination, so as totransmit the generated fee information to said IP charging managementapparatus or said PSTN charging management apparatus on the callorigination side.